1. Field of the Invention
The present invention generally relates to a structure of a vehicle seat, and in particular to a structure of seat cushion frame in the vehicle seat.
2. Description of Prior Art
Among vehicle seats, there is known a bench seat on which at least two passengers can sit. Such bench seat includes a seat cushion frame which is generally of a rectangular shape comprising a forward frame member, a backward frame member and a pair of side frame members connected between the forward and backward frame members. In some bench seats, each of their backward frame members employs a square frame member having a rectangular cross-section to give a reinforcement effect enough to withstand a great backward load applied to the seat cushion frame.
Conventional seat cushion frame of this sort is of such a construction wherein a pair of vertically extending plate-like side frame members are at their respective backward end portions fixedly connected as by welding to the respective two ends of the square backward frame member, and a tubular forward frame member is firmly connected between the two forward end portions respectively of those two plate-like side frame members. Also, a pair of reclining devices are provided in this cushion frame such that the two lower arms of the reclining devices are each fastened to the respective two backward end regions of the two plate-like side frame members.
According to that conventional seat cushion frame, both two lower arms of the reclining devices are situated at a point above the afore-said square backward frame member and also each of such two lower arms is fastened to each outer surface of the two plate-like side frame members. Dynamically, it therefore follows that, when a great load is applied in a backward direction to a seat back frame which is connected via the reclining devices to the seat cushion frame, the great load is transmitted via the two lower arms of the reclining devices to both two side frame members of the seat cushion frame. This will result in the two side frame members being deformed and broken due to the great load, and thus, there is a need to reinforce the side frame members themselves by fixing a reinforcement plate or the like thereto. However, such additional reinforcement will increase the weight of the seat cushion frame.
With the above-stated drawbacks in view, it is therefore a primary purpose of the present invention to provide an improved structure of seat cushion frame which is lightweight and simplified, while protecting its two side frame members against deformation due to a great load applied thereto.
To achieve such purpose, the structure of seat cushion frame in accordance with the present invention basically comprises:
a forward frame member which faces to a forward side of seat cushion frame;
a square backward frame member having a generally rectangular cross-section, which faces to a backward side of seat cushion frame;
a pair of side frame members, each having a vertically extending wall area, said pair of side frame members being securely connected between the forward frame member and square backward frame member; and
a reclining means having a pair of lower arms;
wherein each of the pair of lower arms is fixedly secured to each of the pair of side frame members at securing points defined on the foregoing forward and backward sides in relation to a central axis of the square backward frame member, and wherein such securing points are disposed on the same level with or adjacent to the central axis of square backward frame member.
Accordingly, when a great backward load is applied to the seat back frame, the load is dispersed via the lower arms of reclining means, and simultaneously, downward force components are generated form the load and exerted upon the above-stated two securing points. Such downward force components are immediately transmitted via the two side frame members to the square backward frame member, whereupon most of the great load is received by the square backward frame member and immediately transmitted to the connecting means and escaped in a direction to a vehicle floor. Thus, the great load is not directly exerted on the side frame members, but smoothly transmitted to the square backward frame member, thereby preventing deformation of the seat cushion frame and eliminates the need for reinforcing the same.
Preferably, the afore-said securing points may be defined at backward end areas respectively of the pair of side frame members, and at least two bolts are used to secure said pair of lower arms at said securing points to the vertically extending wall area of each of the two side frame members.
In one aspect of the present invention, the connecting means may be provided between the square backward frame member and the floor of vehicle, so that the great load is escaped through the square backward frame member and the connecting means down to the floor of vehicle.
In another aspect of the present invention, the structure of seat cushion fame may be combined with a slide rail device to be fixed on the floor vehicle, and the connecting means may be provided between the square backward frame member and the slide rail device, so that the great load is escaped through the square backward frame member, the connecting means and the slide rail device, down to the floor of vehicle Other features and advantages of the present invention will become apparent from reading of the description hereinafter, with reference to the annexed drawings.